cc: Split animating and drawing into separate actions

Split impl-side animating and drawing into separate actions. This is
needed to allow for the possibility of a commit between animating and
drawing so that the main thread gets a chance to consume the new
animation state. In particular this allows the main thread to
synchronize with a fling animation using an onscroll handler.

BUG=347366,368064

Review URL: https://codereview.chromium.org/206793003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@267338 0039d316-1c4b-4281-b951-d872f2087c98
19 files changed